It is well known that osteogenesis in a living body can be stimulated by the application of suitable electric signals to the body. In Brighton et al. U.S. Pat. No. 3,842,841, for example, it is proposed to promote bone fracture healing through the use of a constant current applied between a cathode inserted into a fracture site and an anode taped to the skin. The current is supplied from a power pack strapped to the limb of a patient or to the outside of a cast encasing the limb.
Non-invasive techniques utilizing coils or electrodes energized by pulsed or undulating signals for the therapeutic treatment of cells and tissue in a living body have also been developed, as disclosed in Manning U.S. Pat. No. 3,893,462 and Ryaby et al. U.S. Pat. No. 4,105,017. In the former, electrodes or coils supplied with an undulating signal having a waveform whose rise time differs from its fall time are used in the treatment. Both the electrodes and the energy source may be cast in a potting compound compatible with the environment of the body, or embedded in the cast used to immobilize or support the limb of a body. In the latter, the treatment is adapted to be effected by coils in a treatment unit which may be strapped to the leg of a patient or incorporated in a cast and which may be plugged in to an external source of electrical energy in the form of current pulses of specific time-frequency-amplitude relations.